Photographic and imaging systems are primarily designed for use in creating two-dimensional images. In a two-dimensional image, only one perspective is needed. Human vision, however, views scenes from two perspectives with one perspective provided by each eye of an observer. The parallax that exists between the perspectives is interpreted by the mind of the observer to provide depth information about the scene being viewed. Various electronic and photochemical imaging techniques have been developed that capture images of a scene taken from different perspectives. These images are later processed and displayed to a user so that one eye of an observer is exposed to an image of the scene from one perspective while the other eye of the observer is exposed to another image taken from another perspective. This creates the parallax difference necessary to create the appearance of depth in the mind of the observer.
Only two images are necessary to create this appearance of depth. Stereo imaging systems are known that present pairs of images of a scene that are taken at different perspectives to different eyes of an observer. Such stereo systems create a useful depth view of a scene as it appears at one viewpoint relative to the scene. However, to provide a depth image of a scene having an improved appearance, more than two images can be incorporated into a single display. This permits a user to simulate the experience of looking around an object to view subject matter in depth from more than one viewpoint. An example of a display system that provides such a look around effect is found in commonly assigned U.S. Pat. No. 5,715,383 entitled “Compound Depth Image Display System” filed by Schindler et al. on Sep. 28, 1992.
In all multi-perspective imaging systems, the apparent depth in the scene is proportional to the extent of the parallax-induced differences between the presented images. The extent of such parallax-induced differences is determined in part by the degree of separation between the captured images and in part by the distance from the captured images to the scene. Typically, depth imaging systems combine images that are captured at generally the same distance from the scene. This simulates the way that the eyes of a human observer will see a scene. Accordingly, the apparent extent of depth in the resultant output is typically modified by varying the degree of separation between the captured images. This creates an important issue for a photographer in preparing a multi-perspective image: the challenge of selecting the proper combination of images necessary to provide a desired depth effect.
In some cameras and photography methods this challenge is met by the use of cameras that have a fixed separation between the images and thus, the perspective is pre-selected. For example, it is known to capture stereo and depth images using cameras having multiple image capture systems to record multiple images of a scene. See for example, commonly assigned U.S. Pat. No. 6,271,876 entitled “Using Two Different Capture Media to Make Stereo Images of A Scene” filed by McIntyre et al. on May 6, 1997. See also U.S. Pat. No. 4,967,276 entitled “Apparatus for Formatting and Viewing a Stereoscopic Video Frame” filed by Gallaher. Alternatively, it is known to use a camera that provides a single optical path and that is moved along a fixed track. See also U.S. Pat. No. 5,883,695 entitled “Method and Apparatus for Producing Stereoscopic Images with Single Sensor” filed by of Paul on Sep. 19, 1997. See also U.S. Pat. No. 5,325,193 entitled “Single Camera Autostereoscopic Imaging System” filed by Pritchard on Oct. 20, 1992. In such systems, different perspectives are captured as the camera is moved to fixed locations along the path.
What is needed is a system that permits a photographer greater control in selecting the extent of separation between images and therefore the extent of the apparent depth in an image. This control can be provided by allowing the photographer to selectively position the camera to take individual images of the same scene from selected perspectives. These images are later reassembled to form a multi-perspective image. The images can be combined using polarizing techniques and viewed through polarizing glasses. An example of a photography system and method of this type is found in U.S. Pat. App. Pub. No. 2002/0021354 entitled “Image Sensing Apparatus”. One difficulty in using systems and methods of this type is that it is often difficult for the photographer to know at the time of capture what effect the combination of images will achieve when they are eventually rendered. Where the photographer is not satisfied, the photographer must reestablish the scene and use an iterative process to create the desired image. This iterative process can become time consuming and burdensome particularly where the multi-perspective image incorporates images that are captured at three or more different perspectives.
However, in giving the photographer greater control, it is important to provide the photographer with the ability to predict how the resultant multi-perspective image will appear when rendered. Cameras that provide a verification system of individual images captured by a camera do not solve this problem because they are typically adapted to show only one captured image at a time. Even where such cameras are adapted to show more than one image at a time, they do not separate the perspective images in a manner that creates the parallax necessary for the image to appear in depth.
Thus, what is needed is a photography method and a photography system that permits a photographer to see a preview or verification representation of a multi-perspective image during composition and afterward.